This application is based on and incorporates herein by reference Japanese Patent Application No. 2001-217857 filed on Jul. 18, 2001 and Japanese Patent Application No. 2002-150718 filed on May 24, 2002.
1. Field of the Invention
This invention relates to a vehicular communication system for communicating information among various electronic devices installed in a vehicle.
2. Description of Related Art
In vehicles, and particularly cars, the number of electronic devices such as control units, information devices, and audio devices mounted in the vehicle has been increasing, and linked operation and information sharing among these electronic devices is becoming necessary.
Because of this, in related art, those electronic devices mounted in a vehicle among which linked operation and information sharing is necessary have been connected by dedicated communication lines to form information communication networks (so-called vehicle LANs), so that information can be transmitted and received among the devices.
However, in recent years, as the number and variety of electronic devices has increased and the capabilities of these electronic devices have improved, the number of networks to be built into vehicles has also increased, and as a result of this it is becoming difficult to install the communication lines for these different networks in the vehicles.
That is, currently, because vehicles are tending to become smaller as fuel prices increase, the space available in vehicles for installing communication lines is becoming smaller. Furthermore, since, as mentioned above, the number of communication lines required to be installed in vehicles is increasing, designing layouts for these communication lines at the time of vehicle design is becoming difficult, and the work of installing the lines during the actual manufacture of the vehicle is also becoming difficult.
As a result, there has been the disadvantage that the labor expended in vehicle design and vehicle manufacture for constructing these various networks in vehicles has become considerable, and is leading to considerably increased vehicle cost.
The present invention addresses the above disadvantage. Thus, it is an objective of the present invention to provide a vehicular communication system, which allows transmission and reception of information among various electronic devices installed in a vehicle without requiring a relatively large number of communication lines that connect the electronic devices.
To achieve the objective of the present invention, there is provided a vehicular communication system that communicates information among a plurality of electronic devices installed in a vehicle. The vehicular communication system includes a plurality of communicating means for communicating information, and each communicating means is provided in an associated one of the electronic devices. The plurality of communicating means is divided into groups of communicating means. Each communicating means of a given group communicates with the communicating means of the same group using one of a predetermined communication frequency and a predetermined code, which is allocated to the given group and is different from that of any other group.